Microburet or pipet



Patented Dec. 23, 1952 "STATES OFFCE `MICROBURET OR "PIPEI Roger"Gilmon't, Brooklyn, N. Y., assigner to The Emil GreinerCnmpany, NewYork, 1N. Y.,.a:corporation of "New York Applicationseptember 14, 1948,'Serial No. 49;187

Theinventionhereindisclcsed v'rela'testo burets :and pipets pf the-capillary type.

llt is known "that the diiiiculty in handling "these-devices increaseswith the use of capillary Itubing-since `the effect of surfaceAtension'becomes increasingly evident as the 'sizeof the capillarydecreases, leading 'to drainage verrors vwhich vitiate 'the i'accuracyof measurement.

lGlbje'cts-of -the present invention are to effect the eliminationc'fdrainage errors and to provide can extremely -accurate and sensitivemicroburet for Jpipet lf fsimple, -inexpensive structure which 4'can'ibe easily `adjusted and -quickly and easily fread -as 'the adjustmentsare made.

'Important objects of the invention 'also are tc vpr-oviid'ea'structurefo'f the Ycharacter indicated `ul'lich will be adapted andsuited to the many land varioustitration problems involved in analyticalchemistry, both liquids vand gases.

Other desirable "objects rvattainedby the invention and the novelfeatures of construction through which such objects are attained are setforth or will yappear inthe course of the following specification.

The drawing accompanying 4and forming part of the specificationillustrates present practical commercial embodiments of the invention.Structure, however, may -be modied and changed as regards suchillustrations, all lwithin the-true `inten-t 4and broad scope oftheinvention fas hereinafter defined and claimed.

Fig. l in "the drawing is Aa `top plan view r0f foneV o'f 'the `newmicroburets;

Fig. 2 is a front elevation of the same;

Fig. 3 is an enlarged broken sectional detail of thevrotatable andseparable connection between the fine adjusting screw and the spindle ofthe microgauge;

Fig. 4 is an enlarged broken sectional detail of the mercury reservoirstructure and piston at the base of the capillary tube;

Fig. 5 is a plan view of a micropipet instrument with portions shown incross section.

In Figs. l and 2 the microburet is shown as made up of a base 1 on whichthere is mounted a direct reading microdial gauge 8 adjusted by a linescrew 9 and in turn connected to actuate a piston I0 operating in analigned, transversely disposed mercury reservoir II at the base of acapillary tube I2. looped at the top at I3 in gooseneck formation andterminating in a downwardly directed, nne orice I4.

The gauge is suitably calibrated, as to read directly in .0001 cc.divisions and is shown mounted by screw I5 on an upstanding boss or l2Claims. (Cl. 1222-446) iii) stud I`6 on the `basein "horizontal position'with its spindle :I 'I exposed atone end V*to theadjusting screw and atthe opposite end to thepiston'rcd lor element I0.

The 4-ne screw '9 `is 'shown 'as oi'lerating v'iin ra screw post IB y'onthe ba-se 'and as 'havingfaknob -or operating crank It@ Vat `outer vendland a -^cou pling 20 'at the inner end, lthe latter v'carrying a thumbscrew l2I engaging in an 'annular `'groove `212 in the gauge spindle itcprovide a rotatable and separable connection 'between `.the adjustingYscrew rand spindle.

The "gauge spindle is shown ashavingsa direct positive screw 'connectionl23 with the l end 'o'f "the, piston element I-li.

The transversely disposed mercury reservoir at the flower fend of thelcapillary itube vis shown as utilized for mounting this tubing bygripping it 'between opposed screw 'plugs or 'bushings iu, '25,fengagedin lspaced studs y'or posts 226, 2:'1, rising from the base.

The closed end 28 of the reservoir for piston chamber is :shown inFigflias setting in fa socket 129 iin the lend 4o vscrew plug 24, backe'd 'up-by ra cushioning disc 0r 'washer 30.

"The-Opposed companion screw v.plug :25 i's-esh'own .in Ei'g. 4 ashaving la bcre C31 itc freel-y `pass the piston ielement fand -a `socket'32 'to .accommodate the fopen 'end -of fthe reservoir chamber and thepacking washer 233.

`lilljustrnent -Uf the :screw zplugs '12:1 fand 25 :clamps fthe`capillary .tube .in proper relatinn on fthe stand 10i Jvvith ltheipacking `.washer 33 properly sealing the piston where it passes intothe reservoir chamber.

The upper portion of the capillary tubing is shown as supported and heldto the stand structure by a clamp 35.

By the means described the cooperating parts Of the instrument areproperly aligned but removably supported on the base.

Additionally, the base may carry one or more upstanding rods or postssuch as indicated at 36 for carrying test tube clamps or clamps for rstirring devices or the like which might be used in titrationoperations.

, Minute adjustments of the ne screw will show clearly on the directreading micrometer gauge, and these adjustments will be mechanicallytransmitted to the mercury piston through the medium of the gaugespindle, the mercury operating as a liquid piston to deliver thetitration liquid previously charged in the capillary tubing ahead of themercury.

' The rod I0 forming the piston is 0f the same cylindrical dimensionsthroughout its active eX- tent so that equal movements of the same willcreate equal volume displacements and these are directly and immediatelyreadable on the dial of the gauge.

The instrument, therefore, is both sensitive and accurate withpossibilities of error practically eliminated.

The invention may be embodied in micropipet form as illustrated in Fig.5, which shows a pipet tube 31 having a mercury chamber 38 at the end ofthe same receiving a cylindrical piston 39 connected at 49 with thespindle 4l of the microgauge 42.

A micrometer screw adjustment effect is obtained in this instancethrough the differential action of different pitched screws 43, 44, onthe spindle and on a surrounding sleeve 45, respectively, these twodifferent screw elements being engaged by corresponding pitch internaland external screw threads 46, 41, on a micrometer sleeve 48 having afinger knob or disc 49 for turning the same.

The screw sleeve 45 is slidingly mounted on the tubular guide 50 for thegauge spindle but is held against rotation thereon by a pin 5|projecting from the bushing through a slot 52 in the sleeve so that withrotation of the screw the spindle will be advanced one way or the otheran amount equivalent to the difference in pitch between the two sets ofscrew threads 43 and 44.

While particularly designed for micro or ultramicro operations, it willbe appreciated that the invention may be used for macro work as well, inall cases providing a high degree of accuracy and quick, easyreadability in a simple, low cost, structural form. The invention isequally well suited to gases and liquids and in any volume. If theliquid which is to be handled reacts with mercury then the liquid alonemay be used, without mercury.

What is claimed is:

1. A microburet or micropipet comprising tubing having a small dischargeorice at one end and a displacement chamber of larger dimensions at theopposite end, a piston rod of uniform dimensions'mounted to operate inthe end of said displacement chamber, a direct reading gage having anoperating spindle, means securing said gage with one end of saidoperating spindle in alignment and engagement with the outer end of saidpiston rod and an adjustment screw in alignment and connected with theopposite end of said spindle and whereby ne adjustments of said screwwill actuate the spindle of said microgage and said spindle at the sametime will transmit displacement adjustments to said piston rod.

2. A microburet or micropipet comprising a base having horizontallyspaced, upright supports, screw plugs mounted in horizontally opposedrelation in said supports, said screw plugs having horizontally opposedsockets in the inner ends of the same, a length of tubing having itsopposite ends seated in and removably held in the sockets of said screwplugs, a capillary tube in communication with and extending upwardlyfrom the intermediate portion of said tubing, said tubing being oflarger diameter than said capillary tube to constitute a reservoir formercury or titration fluid, said capillary tube having a gooseneck atthe upper end of the same terminating in a downwardly directed capillarydischarge orifice, one of said screw plugs having an opening through theend of the same in line with said tubing, a piston rod of uniformdimensions extending through said opening into the tubing, packing inthe seat in said plug at the end of the tubing engaged in said seat andsurrounding said piston rod, a direct reading microgage having a plungerfor operating the same, means supporting said microgage on said basewith one end of said plunger in alignment and engagement with the outerend of said piston rod and whereby said piston rod will be actuated bysaid microgage plunger, and an adjustment screw mounted on the base inalignment and engagement with the other end of said microgage plungerand whereby fine adjustments of said screw imparted to the plunger ofthe microgage will be transmitted by the plunger to said piston rod toeffect displacement of contents of said reservoir tubing in respect tothe capillary tube connected therewith.

ROGER GILMONT.

REFERENCES CITED The following references are of record in the rile ofthis patent:

UNITED STATES PATENTS Number Name Date 215,300 Sherman May 13, 1879635,154 Smreker Oct. 17, 1899 2,158,774 Grubelic May 16, 1939 2,412,295Shaier Dec. 10, 1946 2,464,714 Peterson Mar. l5, 1949

